Fernandes Sofia R, Salvador Ricardo, Wenger Cornelia, de Carvalho Mamede A, Miranda Pedro C
Annu Int Conf IEEE Eng Med Biol Soc. 2016 Aug;2016:3121-3124. doi: 10.1109/EMBC.2016.7591390.
Transcutaneous spinal direct current stimulation (tsDCS) is a recent technique with promising neuromodulatory effects on spinal neuronal circuitry. The main objective of the present study was to perform a finite element analysis of the electric field distribution in tsDCS in the cervical spine region, with varying electrode configurations and geometry. A computational model of a human trunk was generated with nine tissue meshes. Three electrode configurations were tested: A) rectangular saline-soaked sponge target and return electrodes placed over C3 and T3 spinous processes, respectively; B1) circular saline-soaked sponge target and return electrodes placed over C7 spinous process and right deltoid muscle, respectively; B2) same configuration as B1, considering circular shaped electrodes with sponge and rubber layers and a small circular connector on the top surface. The electric field distribution for cervical tsDCS predicted higher magnitude in configurations B1 and B2, reaching a maximum of 0.71 V/m in the spinal white matter and 0.43 V/m in the spinal grey matter, with values above 0.15 V/m in the region of the spinal circuits related with upper limb innervation. In configuration A, the values were found to be <; 0.15 V/m through the entire spinal cord. Electric fields with magnitude above 0.15 V/m are thought to be effective in neuromodulation of the human cerebral cortex, so the configurations B1 and B2 could be an optimal choice for cervical tsDCS protocols. Computational studies using realistic models may be a powerful tool to predict physical effects of tsDCS on the cervical spinal cord and to optimize electrode placement focused on specific neurologic patient needs related with upper limb function.
经皮脊髓直流电刺激（tsDCS）是一项新技术，对脊髓神经回路具有潜在的神经调节作用。本研究的主要目的是对颈椎区域tsDCS中电场分布进行有限元分析，研究不同电极配置和几何形状的影响。利用九个组织网格生成了人体躯干的计算模型。测试了三种电极配置：A）分别将矩形盐水浸泡海绵靶电极和返回电极置于C3和T3棘突上；B1）分别将圆形盐水浸泡海绵靶电极和返回电极置于C7棘突和右三角肌上；B2）与B1配置相同，但电极采用带有海绵和橡胶层的圆形，并在顶面有一个小圆形连接器。颈椎tsDCS的电场分布预测显示，B1和B2配置中的电场强度更高，在脊髓白质中最高可达0.71 V/m，在脊髓灰质中为0.43 V/m，在与上肢神经支配相关的脊髓回路区域中值高于0.15 V/m。在配置A中，整个脊髓的值均<0.15 V/m。电场强度高于0.15 V/m被认为对人类大脑皮层的神经调节有效，因此配置B1和B2可能是颈椎tsDCS方案的最佳选择。使用真实模型的计算研究可能是预测tsDCS对颈脊髓物理效应以及根据与上肢功能相关的特定神经疾病患者需求优化电极放置的有力工具。
